1640731 has 4 divisors (see below), whose sum is σ = 1668600. Its totient is φ = 1612864.

The previous prime is 1640729. The next prime is 1640741. The reversal of 1640731 is 1370461.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1640731 - 2¹ = 1640729 is a prime.

It is a super-2 number, since 2×1640731² = 5383996428722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1640701) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13846 + ... + 13963.

It is an arithmetic number, because the mean of its divisors is an integer number (417150).

2^1640731 is an apocalyptic number.

1640731 is a deficient number, since it is larger than the sum of its proper divisors (27869).

1640731 is an equidigital number, since it uses as much as digits as its factorization.

1640731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27868.

The product of its (nonzero) digits is 504, while the sum is 22.

The square root of 1640731 is about 1280.9102232397. The cubic root of 1640731 is about 117.9448895196.

The spelling of 1640731 in words is "one million, six hundred forty thousand, seven hundred thirty-one".